No problem, but now you're going into territory that I have no experience with as I'm not military.

But your USERRA is what's governing here. The airline has pretty much no say. Unless, like I mentioned, the mill leave wasn't legitimate and was getting abused. It's happened. And just about every airline out there is accommodating to service members, so don't feel as if it's "frowned upon", or will reflect negatively on you at the company what so ever.

It's not at all uncommon of a guy to get hired (anywhere), complete his IOE, get signed off as good to go, then go back into his guard/reserve unit right away. Or simply do his month to month line flying and getting his trips, or portions of trips dropped to fulfill the commitment.