Whistling sound coming from motor.

[cotetoi]

I started my Helix yesterday after a two week spell. I noticed a whistling type noise coming from the motor. I remember that it started during my last ride but I thought it was normal. I am just wondering if it is normal or a symptom of something wrong somewhere. I haven't ridden it for 2 weeks.
Any thoughts would be helpful and appreciated. I searched the topic but nothing comes up.
Jay.