[conman]

Just came back from Hcmc and thus have a question for the regulars. I was in Hcmc last month for 4 days and went there again last Friday for a 3 days trip. When I reached the immigration last Friday, the officer suddenly asked if the guy behind is with me. I said no and he asked what am I there for? I told him visit relative and he stamped my passport. This is the first time I've been questioned this way as I travel quite often to Asean countries on a monthly basis. Are the immigration in Vietnam very anal about multiple entries on a monthly basis?