I'd definately have it checked out even if only for peace of mind. Last thing you want is for a string break that could cause injury. [&:]

Do you have any idea how many shots you have on the string? Most manufacturers have recommendations on how often they should be replaced. From what I understand 2000-3000 shots is about average for a string. Your local shop should be able to tell you for certain if the string and/or cable slide need replaced. If they have to replace the string they will most likely recommend replacing the cable too. If it were me I'd replace both at the same time.

If a new string gets installed it will stretch some. Depending on the materials some strings stretch more than others. This can be time consuming if you don't have your own bow press. Once the string stretches you'll have to go back to the shop and have them press the bow so that they can put some twists in the cable to compensate for the stretch. If not your ATA, brace height, etc. will all be out of tune.