I'm using Seaborn, instead of the artist label I get _child0 for example (number is specific to a line). Interestingly on version 0.5.2-2 (apt default) the label shows intermittently, moving to 0.5.3 (pip latest/default) only x and y.
df = pd.DataFrame(pandas_dict_for_dataframe)
dfm = df.melt('Date', var_name='Item', value_name='Price')
g = sns.catplot(x="Date", y="Price", hue='Item', data=dfm, kind='point', height=8, aspect=16 / 8., dodge=2)
plt.xticks(rotation=45, ha='right')
mplcursors.cursor(hover=True).connect("add", lambda sel: sel.annotation.set_text(sel.artist.get_label()))
plt.show()