Hmm, have you had the gun since new? Assuming the spring is tight on the guide, it would sound like the gauge of spring wire is too big, maybe suggesting it's not OEM spec. If it's not tight, I would certainly be suspicious. I've not had mine apart, so can't comment on the correct wire gauge. Has it just started doing this, or done it for as long as you have had the pistol? Replacement springs are in stock at Chambers. https://www.gunspares.co.uk/products/24564/HW45/
If you've had it since new, maybe it's just a tolerance issue. If there is no sign of metal flakes/chips visible through the slot, it may just be one of those mildly annoying things one puts up with, but it doesn't sound right.