Your two scenarios make sense. You didn't specify the security so I'll toss a third one out which applies to options.
I'm looking to roll a somewhat deep ITM long put down a strike for a credit of $4. The B/A spread on each side is quite wide so I place a vertical spread order for the roll, splitting the B/A on each leg. I don't care what the fill price is for each leg as long as I get my $4 credit. Once in awhile, one or more spread has legs that are filled are well away from the current B/A.
For example, all but one spread are filled at $3 for the buy and $7 for the sell, netting me my $4. The outlier spread is filled at $3.50 for the buy and $7.50 for the sell, again netting me my $4. No advantage or disadvantage to me. However, my fill prices on the outlier are well outside the current B/A spread. This could occur just as well between the B/A spread that you noticed (no Time and Sales quote but it trades there).
My guess is that there's a call buyer or call seller at one of my strikes who either split the B/A poorly or didn't split it at all. The market maker doesn't want that risk so he combines the 3rd party's call with one of my puts in a conversion or a reversal and then fills my other leg $4 away. IOW, he's splitting the B/A for me (capturing half the B/A of my puts) and capturing the bulk or all of the call's B/A spread from the 3rd party.