Fuel Filter: Bottom bolt missing?

I went to go change my fuel filter for the first time the other day (2.7) - first since I've had it and what I thought was perhaps the first time it had ever been changed. When I got done loosening the lines, I went for the mounting bolts - the top isn't hard to get to but I was thinking how much of a pain it would be to get to the bottom. Upon loosening the top however the thing just came loose so I was puzzled - long story short; there was no bottom mounting bolt. I checked the filter mounting bracket and you could see the imprint on the top where a bolt had been - on both sides of it, but the bottom appeared as if a bolt had never been on it.

Is this common? Did some assemblers just omit the bottom bolt cause its a bitch to access? Should I try and find another bolt for the bottom or will a tight top bolt be sufficient?

 

I remember that thing feeling pretty secure after just one bolt, but if it were me I'd pull the top one at the hardware store and get its brother back. Wouldn't sit right having found out about it.