I had that happen going from L1-L2...I wasn't as learned about training as I am now (and I'm still no expert).

I ignore the "your team needs X training sessions" message and just do trainings until I'm back at Max Bonus--10% team, 10% all (unless I pick up a transfer). I don't think those automated messages really have any impact on your performance...just my $0.02 worth.

Good luck, & keep plugging!