Maybe he was trying to get more points. I've been told that if you surrender to a weaker team that the MMR will give you higher points afterwards. I tried it a couple of times, but it didn't work for me. Do you remember the last team you used?
Was attacked twice in PvP tonight , by a whale with 47 champed 5 stars (450-475) . I have 2. (450) He lost both times . Possibly he surrendered because I have no rational explanation how he could lose to me .
Probably he was using Polaris/BRB and Kitty to take down your team. Your AI matched away their protect tiles and Polaris didn't have any chance to multiply them. Next, they made a match and cascaded into 5 or 6 teamup and it downed their Polaris the next one or two turns. Britty decided to retreat because using one healthpack is better than using three.