"p23 ab IgM reactive" "p41 & p39 non-reactive" do I have Lyme disease, or can something else cause this? (diagnosed w/ rheumatoid arthritis 7yrs ago.)

Complex. The diagnosis of lyme disease is usually on a clinical basis. Serologic testing should not be done for screening purposes. False positive results are very frequent in patients with autoimmune diseases, particularly rheumatoid arthritis, and particularly when these are IgM antibodies.
Get a diff. test. The test you had doesn't clearly confirm or eliminate lyme disease as a diagnosis. You need a more specific tests that has all the "species specific" antibodies of a lyme spirochete. Igenex labs in palo alto ca has the best lyme antibody test I have found. You can contact them and get a kit sent to you but your doc has to order the test.