Yes, the term is called "compacted" and it is not a good thing. You need to take a stick or something similar and loosen the soil up especially the top layer. You also need to flush thoroughly to get all the salts down to a normal level. The problem you have, can be avoided in the future if you re-potted regularly and is not so much of a problem if your only growing for a few months. You are looking at 16 months of un-used fertilizer in a small space if I did my math correctly! If your gonna grow for that long a flushing every three months or so will also keep this from happening.