Do you routinely see this with your hips? We have had a long fall without a hard freeze and there are lots of hips doing this. I’ve seen it in the past, but more so this year. The roses that tend to do this are roses like the Morden series and Buck roses. It kind of seems like the hips have fully matured and the outter surface dries and cracks ad then the hip insides become a little bit on the drier/mealier side as it seems almost stringy as time goes by. It almost seems like it may do this in part to emit more fragrance for animals to be attracted. It is helpful if I collect the hips before this point for seed extraction as it is less messy to get the seeds out. The polyantha roses and roses like R. setigera, R. rugosa, and a good number of other roses don’t seem to do this.