The other point I would add, based on experience, is that sometimes the person popping in believes something may be awry when it's not, then either tries to address that or contacts you to mention it, causing undue worry at your end. On that basis, and given that a couple of days without food is definitely fine, I would leave the situation as it is on this occasion.
For longer stays away, it's obviously a different matter - which is when you could employ Sue's great suggestion or else use an auto-feeder.
