are you taking any magnesium? Or eating mag rich foods?

The first thing to consider with muscle tightness is magnesium.

Calcium causes muscles to contract. Magnesium helps relax them.
So anything that causes increased ratio of Cal/Mag can cause problems.

Increased calcium intake without taking mag is one cause. But there are
medical conditions that will increase serum calcium also.

If this is "new" to you, this symptom, I'd get some blood tests run at the
doctor.
this site lists causes of elevated calcium:
http://www.nlm.nih.gov/medlineplus/e...cle/003477.htm

If you have been "overusing" those muscles, simple soaks in a hot tub, or
brief heat treatments may help the muscle relax. Heat also helps eliminate
excess lactic acid if that is a problem for you.

Another cause of muscle pain, is low carnitine levels. The muscles overuse
glucose for energy and make too much lactic acid, which hurts. Use of the amino acid carnitine allows the muscle mitochondria to more effeciently use
fatty acids as fuel, and therefore less lactic acid builds up.

Most people get hard muscles in the legs first, since those are the largest muscle groups and work the hardest. To have a bicep problem first, could imply you have some nerve issues in the neck. So keep an eye on that.