Yea I checked the pads out, they all have plenty of life in them. I'll have to keep an eye on it I guess.
TBF you should really fit new pads all round before topping up the fluid.
Just wanted to add to this to help others out if they read this in the future.
When I checked my pads I thought they looked fine, plenty of life in the the fronts from what I could see. I topped up the brake fluid and the problem went. However, upon further investigation a week or so later I noticed that the front pads infact were not fine at all - basically on both sides the inner pad was worn almost completely down, while the outer pads still had loads of life left in them. I am told that this happens because the inner pad takes most of the hit due to the piston being on the inside - this makes total sense to me now but is something that I was not previously aware of (as I have no previous experience in changing or maintaining the brakes myself).
So the moral is - make sure you check the inner front brake pads, not just the outer!
When I later replaced my discs and pads on the front, the brake fluid level was of course too high and so a lot of what I had previously topped up came back out again.
