I am happy to have received your answer for my query. Nothing serious beyond your stated. Thanks a lot.
May I assume you have done a testicular self-examination?
If so, and everything seems normal, it may just be that the hard surface is causing pressure or tugging on the internal structures (vas diferens, epidemis, testicles) of the srcotum. If you can't avoid long periods of time in hard chairs, if possible, try to bring along a cushion or folded towel to prevent the dsicomfort.
If you hve not done the self-examination, gently explore the entire scrotum, observing for lumps, hardened ares, swelling, etc. (Men should do this on a monthly basis, just as women should do monthly breast self-examinations). If anything seems amiss, schedule an appointment with a family doctor or urologist. If this is difficult for some reason, you might get a professional response by posting your question in the "Ask a Doctor" Expert Urology Forum.
By the way, you accidentally posted in the wrong forum. (Don't be concerned, newcomers do it all the time, and the moderator will transfer your question to a more appropriate forum.)
Regards...