Hiya Naomi
,
I know the noise you mean and i am quite sure that it is normal for Robos to make this noise occasionaly - some of mine make this noise, and it happens with all ages, so it is probably nothing to worry about.
but, just be careful that it isnt an allergy, if you have maybe changed his food or bedding etc. or used anything diferent in the house - but if you havent changed anything then i am sure it is nothing to worry about
Tammy x