actually, if you're a grown up, it's actually easier to pick up musical instruments due to it being an objective oriented exercise.
the average population of adults behave in a manner in which they exhibit behaviour to meet an objective. they work to earn money. they drink to get drunk and pick up girls. etc.
in this case, the objective/goal is to learn how to play the violin, and assuming that the original poster falls under the 95% standard distribution of population, he shouldn't have an issue with picking it up. the fact that he/she is also grown up means that he/she has ability to set clear (and possibly more realistic) goals in terms of musical growth and learning.
the most important aspect that one must remember is the ability to sustain an interest in it. I've recently picked up learning the electric guitar again, and though I might have had prior experience in learning it many years ago, I feel that my age has put me in good stead for this.