Came in contact with someone with mrsa, what should one do?

Nothing: It means nothing, just wash your hands well and do all the normal things to stay healthy like eating right and sleeping well and drinking plenty of water. Mrsa is just a resistant strain of staph bacteria, not an actual disease you can contract.

Not to worry...: As long as this was casual contact, and you have no open sores/wounds and are not immune suppressed, you really don't have to worry about becoming infected. Use good handwashing, and if you live with the person, cleaning bathtubs, sinks, countertops etc. With bleach solution is the best way to eradicate this bacteria.

Clean the skin: Careful skin cleaning is usually sufficient. With any sign of a rash use a cleaner like hibiclens.