I've had this happen occasionally on iPhone 5.
Just tried and had it happen but can't replicate now, may have been while MW was syncing that it happened. Currently iOS 8.4 MW 2.0.6 but has happened on previous iOS and MW.
1 Started app
2 Went to account
3 tapped '+'
4 entered Payee and amount
5 tapped Date & time
6 tapped time
7 time showed then reverted to date
8 tapped time goto 7
tapped < then 1 - 6 was fine transaction completed
I was unable to reproduce this issue either. If anyone reproduces this again, please write to us directly at email@example.com. Thank you!