Getting Error with pushing view on NavBar - iphone

Question

When I push a view, I am getting the following errors in the console:
nested push animation can result in corrupted navigation bar
Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.
Any ideas how to fix this?
This is the method that pushes the new veiw:
- (void)calendarMonthView:(TKCalendarMonthView *)monthView didSelectDate:(NSDate *)d {
NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss Z"];
[formatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"GMT"]];
NSString * dateString = [formatter stringFromDate:d];
if ( [data containsObject:dateString] )
{
NSDate * searchDate = [formatter dateFromString:dateString];
NSCalendar * calendar1 = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDateComponents * dateComponents = [[[NSDateComponents alloc] init] autorelease];
[dateComponents setDay:1];
NSDate * searchDateEnd = [calendar1 dateByAddingComponents:dateComponents toDate:searchDate options:0];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Session" inManagedObjectContext:self.managedObjectContext];
[request setEntity:entity];
NSPredicate * predicate1 = [NSPredicate predicateWithFormat:#"timeStamp >= %# AND timeStamp < %#", searchDate, searchDateEnd];
[request setPredicate: predicate1];
[request setFetchBatchSize:20];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"timeStamp" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
NSError *error = nil;
NSArray *array = [managedObjectContext executeFetchRequest:request error:&error];
NSLog(#"xxx array: %#", array);
SessionViewController *sessionViewController = [[SessionViewController alloc] initWithNibName:#"SessionViewController" bundle:nil];
self.selectedSession = (Session *)[array objectAtIndex:0];
sessionViewController.selectedSession = self.selectedSession;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"MMM d, y"];
NSString *dateString = [dateFormatter stringFromDate:selectedSession.timeStamp];
sessionViewController.title = dateString;
sessionViewController.hidesBottomBarWhenPushed = YES;
[self.navigationController pushViewController:sessionViewController animated:YES];
[sessionViewController release];
[dateFormatter release];
[sortDescriptor release];
[request release];
[sortDescriptors release];
}
}