Absolutely, you have every reason, for concern. Hope they aren't dismissing things because you have documented depression and anxiety. I find it better to look at overall health where sleep issues are. I have a neurological illness, that's a fall back explanation, for various occassional health concerns. However, even with that, it isn't always not oft the culprit. As a patient, I take steps necessary for better sleep. Sleeplessness can literally mess with my physical health.
Can you limit the oversleeping with establishing a routine of hours awake, hours to sleep?