PCR fluctuating

Hello
I am on imatinib since diagnosis. Recent PCR is 0.013 IS @42 months

@18 month-undetactable
21 month - 0.022
24 month - undetactable
27 month - undetectable
33 month - 0.022
39 month - 0.042
42 month - 0.013

Is fluctuations at this level is normal? Should i switch to other TKI? Plz comment.