I think you should at least give him 48hrs before becoming alarmed. I had something sorta similar happen:
I had told a seller that i'd shoot them a Paypal payment the next day when i got outta work. I wake up the next morning and am dying all throughout work. I had a BAD stomach bug. I got home and took a shower and went to bed immediately. The next day i was feeling a little better but still sick. It wasn't until the day after that when the seller contacted me asking if there was a problem. That was roughly 48hrs. By then i was feeling better and explained what had happened and it was all good. In those 48hrs when i was sick as a dog, the thought of "oh i forgot to send that payment!", never even crossed my mind lol. So yes, i can understand how a death in the family could distract the seller. I personally wouldn't worry about it unless i didn't hear anything for at least 48ish hours. I may be more easy going than most people though. I dunno, just me 2¢