No, I'm just not talking about inflation of the same thing.
When people - including economists - just say inflation, that's just an abbreviation for "inflation [of the general level of prices]", out if they're Austrian, "inflation [of the money supply]".
But even if this type of inflation is more commonly discussed, that doesn't mean it's the only, and economists also talk about types (e.g. asset value inflation).
Now, notice I didn't write that Bitcoin is an "inflationary currency", but that it's inflating in value. That's because the former term refers to the first kind of inflation I wrote above, when I'm talking about another.
Why did I use an unconventional type of inflation? Is because while it's technically true that the general level of prices in Bitcoins is deflating, I don't think that's very relevant when almost no product sets its prices in that currency, nor will any economy thus experience any deflation due to it.
At least for now, Bitcoin is more like an asset than a currency, therefore it makes sense to speak of its value inflating, just like we do for other assets.