Refusing pacifier


Maybe a silly question, but my six-week old usually takes a pacifier for soothing/sleep, but the last few days she has been refusing the pacifier and instead immediately sticking her fist in her mouth. Is this something i should be discouraging? The pediatrician (when we asked about pacifiers initially) stated that it was better to use the pacifier instead of letting her suck on her thumb (his reasoning being that the pacifier habit can be broken by simply taking the pacifier away, while a thumb-sucking habit would be harder to correct). So should i keep trying to get her to accept the pacifier again or just let her suck on her hand for self-soothing? Thanks!