Welcome to the HIV forum. I'm glad you used your name at the end; until then, I couldn't tell whether you were male or female. The risks of HIV are far higher, as you undoubtedly know, among men who have sex with men (MSM) than straight men and women.
I agree that your partner's evasiveness when asked his HIV status suggests he likely is infected. In the future, I would advise you to ask that before getting involved, even at the kissing or other no-risk level, e.g. mutual masturbation, frottage (body rubbing), etc. Not because kissing or these other actitivies are risky; they are not. But because one thing can rapidly lead to another, and intentions for safe sex often go out the window in the heat of the moment. Therefore, among MSM frank exchange of HIV/STD status is imperative before any physical contact, not after it gets underway. And of course the corollary is that you won't go ahead with any contact -- and absolutely not with unprotected anal sex -- with those who are positive, don't know, or, like your partner, are evasive about it. Take that lesson to heart, and you'll go a lifetime at low risk for HIV. Ignore it and there's a good chance HIV is in your future.
OK, lecture over. The fact is that HIV has never been known to be transmitted by kissing. That's not to say it is impossible. But in the 30 years of the known HIV/AIDS epidemic, few if any HIV/AIDS experts have ever seen an infected gay/bi man (or any other patient) whose only possible exposure was kissing. The same is true of genital touching, body rubbing, etc. It just doesn't happen. Among other things, saliva inactivates HIV. The presence of a sore throat at the time of the exposure is not likely to make any measurable difference in risk. Just think about it: at any one time, millions of people have sore throats. Thus, over the years there must have been millions of kisses when one person or the other had a sore throat. And still no mouth-to-mouth HIV transmission. So logic tells you that even with a sore throat, kissing carries little if any risk.
Here is a thread you might want to look at, explaining why HIV and other STDs are (and are not) transmitted in certain ways. Start reading with the follow-up comments that start December 14:
http://www.medhelp.org/posts/show/1119533
I hope this helps put things in perspective for you. Stay safe-- HHH, MD