My concern is that I might have gotten HIV if his pre-cum entered through a hemorrhoid while bleeding. I took an HIV ag/ab test Mar 14 (27 days) and it came back negative. 

Is there a need to take another test at 6 weeks? 

Thanks

This was a no risk encounter- no penetration, no risk.  That your hemorrhoids had flared and were bleeding does not change the assessment.  Even if your partner had untreated HIV (most people do not) surface contamination of wounds, scrapes and scratches does not lead to infection.  Remember, the flow of blood was outward and for HIV to infect someone is a wound, infectious material must be introduced deep into tissue, not simply contaminate the surface.  

Your negative test at 28 days provides additional strong evidence that you were not infected.  At that time 99% of persons who had been infected would have positive tests.  Although official recommendations state that tests for HIV are not entirely conclusive until 6 weeks following an exposure, as I said above, 99% of tests are positive at 4 weeks and I have never seen of heard of a person with a negative test at 4 weeks who went on to become positive.  In your situation, I would not worry.  EWH

Just to clear all my concerns up, even if he used the tip of his penis to rub around my my anus and he had pre-cum with my hemorroids it is still a no risk encounter and even a day short of 28 days, my ag/ab 4th gen negative test is conclusive and no further test needed.  

Please don't worry.  EWH