Short call assignment question:

This is a first for me, I think. I was holding an 88/93 BeCS on TSO that expired Friday. TSO closed at 92.43. I had received 2.48 credit for the spread about 2 weeks ago. Today I open my account to see that I’m short a position in TSO at 88. I got TSO called away from me, and the long call I had at 93 was not exercised automatically by TDA. It also showed I was in a maintenance call. Was able to go ahead and buy back the short position, but the rep at TDA couldn’t really explain to me very well why it wasn’t automatically taken care of. Any ideas? Thoughts? Recommendations? Is this normal?
The only good thing out of this was they threw in a few free trades for the hassle.