Call it whatever you want. In the real world, prices of goods and services constantly increase to compensate for the ever expanding supply of fiat which is created out of thin air by the Central Bank. This is called inflation.
As the price per play seems to stay the same, 1 $MUSIC, I would not call it inflation. Also, it is not like $MUSICOIN is 'created out of thin air' but like every other minable coin by hardware resources. correct me if I am wrong.
Musicoin's price has remained more or less constant despite increasing supply only because of high demand. If the price of MUSIC coin started falling due to lack of demand and ever increasing supply, artists would be forced to increase prices to compensate.
If the price for $MUSIC falls miners would stop mining and therefore supply will slow down. As said, it is not premined or created out of air. Now if artists raise their prices and somebody would create more coins out of air then you would have real inflation. Instead, while the price per play increases, the demand of $MUSIC would rise, while supply decreased because of unprofitability in mining. that leads to increasing price of $MUSIC imho.
Like it or not, it's a serious problem. In the month of May and June, all the altcoins have had a massive jump in price but not Musicoin. Why? 164m coins were added to the supply in the last 3 months alone.
AFAIK $MUSIC is listed on bittrex since March 2017 (edit: andcryptopia). So I would also consider the very early phase, missing reputation and not being able to trade on other markets. they just entered too late to catch up on the last boom.
'Were added to the supply' really sounds like someone magically made them appear. they were mined from the very first coin by miners, not one $MUSIC premined. the difficulty is low, so supply is fast right now.
in theory there is no supply cap, but instead there will be a difficulty bomb just like in ETH, wich is planned around a supply of 600mil coins. to me, this is another form of capping supply.
supply speed should also throttle down because difficulty increases. what is left is the demand of coins, wich should only be showing up in form of early investors and speculants, because in this early phase the real demand of $MUSIC for listeners and artists should be in a growing state right now, not a decreasing state...